1. Field of the Invention
The present invention relates to a computer system and a method for controlling transmission of audio signal outputs from the computer system.
In particular, the present invention relates to a computer system utilizing a digital versatile disk-read only memory (DVD-ROM) as storage media for storing both video and audio information, and to a method for controlling audio signals output from the DVD-ROM in the computer system.
2. Discussion of the Background
In recent years, because of the advance of computer technology and multimedia technology, various types of computer systems (e.g., portable type or notebook type computers) have been developed which utilize a multimedia storage device.
Generally, multimedia type computer systems include various devices for reproducing motion picture data, audio data and also text or graphics data.
With recent technological advances of a digital versatile disk (DVD), attention has been directed to utilizing the DVD in a computer system as a new storage media especially in light of the conventionally utilized compact-disk read only memory (CD-ROM).
Presently, a DVD-ROM can store about 4.7 Giga-Byte worth of data on one surface side, which is about 7 times that of the conventional CD-ROM data storage capability. In addition, because the DVD-ROM can store data on both surface sides, it is possible to store as much as 9.4 Giga-Byte worth of data with a single DVD-ROM.
Consequently, the computer system using the DVD-ROM as a data storage device can reproduce a large amount of high quality video and audio data. This means that a movie or other title can be reproduced in the computer system, while maintaining a high picture quality.
To store video data or other information on the DVD-ROM, the video data usually includes presentation data and navigation data. The presentation data corresponds to video objects and generally includes video data, sub-picture data and audio data. The video data is compressed and coded according to a motion picture expert group 2 (MPEG2) standard.
The coding of sub-picture data and audio data is supported by a run-length coding or a Dolby AC-3 coding process. The sub-pictures are bit-map data and are used for superimposing textual information, such as a name of the movie picture, or dialogue on a movie picture and for displaying choices on a menu screen.
In addition, one video object can include video data for one channel, audio data for a maximum of 8 channels and sub-picture data for a maximum of 32 channels, for example.
The navigation data is reproduction controlling data for reproducing presentation data and it is possible to insert a navigation command in the navigation data. In addition, the navigation command may be used to change reproducing contents or the reproducing order of the video data. Thus, it is possible to create an interactive title by defining various multi-point constructions using the navigation command.
For reproducing the title or movie stored in the DVD, the data read from a DVD-ROM drive is stored in a main memory of the computer, and then the stored data is transferred to a MPEG2 decoder. The MPEG2 decoder executes a de-scrambling operation because the coded rows of the video data corresponding to the title are previously scrambled to prevent unlawful copying.
After the de-scrambling operation, the video data, the sub-picture data and the audio data are respectively decoded. The decoded video and sub-picture data is displayed on a display monitor or a television screen by a display controller in the computer. The decoded audio data is reproduced by a speaker through an audio controller included in the computer.
As explained above, the audio data is included in the title stored on the DVD. Further, the audio data is 5.1 channels of data coded by the Dolby AC3 coding process.
To enjoy a surround effect of reproduced audio data, the personal computer may be coupled to an external audio system. This may be achieved by including audio output terminals in the personal computer to couple the computer to an external audio system.
However, a problem occurs when the computer is coupled to an external audio system, due to a built-in speaker included in the computer. That is, for the case of a computer coupled to an external audio system and which includes a built-in speaker, the DVD audio data is reproduced both with the external audio system and the built-in speaker.
This destroys a quality sound balance for the external audio system, due to a down mixing sound from the built-in speaker. In addition, if the built-in speaker is disabled to achieve a desired quality sound balance of the external audio system, warning sounds, such as a system beep cannot be produced.
Consequently, during a reproduction of DVD audio data, it is impossible to inform a user of an abnormal state of the computer, such as a low battery state.
Accordingly, one object of the present invention is to solve the aforementioned problems of the conventional computer system.
Another object of the present invention is to provide a novel method and computer system for controlling a reproduction of DVD audio data through an external audio system with a high quality sound by eliminating an unwanted sound effect from a built-in speaker.
Yet another object of the present invention is to provide a novel method for controlling a reproduction of a warning sound, such as a system beep whenever a system emergency may occur.
These and other objects are achieved according to the present invention by providing a computer system, which includes a built-in speaker, a sound controller configured to receive audio signals, including system warning signals, and configured to supply the received audio signals to the built-in speaker. Also included is a driver configured to drive digital data, including digital audio data, from a digital data storage media, a decoder configured to decode the digital audio data, and a converter connected to the sound controller. The converter is configured to supply analog audio signals to the sound controller by converting the decoded audio data into the analog signals. In addition, a e jack configured to couple the computer system to an external audio system is included along with a detector configured to detect whether the computer system is coupled through the jack to the external audio system.
Also included is a transmission prohibiting mechanism configured to prohibit transmission of the decoded digital audio data to the sound controller when the detector detects the computer system is coupled to the external audio system.
The present invention also includes a method for controlling a computer system, which includes the steps of decoding digital audio data read from a digital data storage media (e.g., a DVD-ROM), and coupling the computer system to an external audio system. Also included is a step for prohibiting transmission of the decoded digital audio data to the built-in speaker when the computer system is coupled to the external audio system, even though the built-in speaker is an active state for reproducing other audio signals than the decoded audio data from the DVD-ROM, such as a system beep sound.
That is, the computer system according to the present invention inhibits the transfer of the decoded audio data to the audio controller when the computer is coupled to an external audio system. Thus, the decoded audio data is supplied only to the external audio system.
Therefore, according to the present invention, it is possible to reproduce high quality decoded digital audio signals from the DVD to the external audio system without negatively affecting a system warning sound, such as a system beep sound from the built-in speaker.